The general purpose of this project is to examine the effects of specific conditions of early visual experience on subsequent mastery of particular discriminations. Specifically, we are interested in the relative influence of simple visual exposure to stimuli vs. "functional" exposure (stimuli correlated with differential consequences) on the young infant's later ability to differentiate these same stimuli. Also of interest is the contribution of active instrumental responding vs. "passive," Pavlovian responding in the functional setting.